In the related art, a vehicle is known which includes a door opening part (backdoor opening part) and in which a backdoor for opening and closing the door opening part is provided. The door opening part is formed by a roof panel that is arranged at an upper position in the gravity direction of a vehicle body, a rear panel (lower back) that is arranged at a lower position in the gravity direction of the vehicle body, and a rear pillar that is arranged at both outer sides in the vehicle width direction of the roof panel and the rear panel and is provided along the vertical direction in the gravity direction so as to connect the roof panel and the rear panel as a main configuration.
The door opening part is a relatively large opening in the vehicle body and is arranged in the vicinity of a rear suspension, and therefore, the door opening part is a region on which stress is easily concentrated. A mode deformation in which the opening is twisted due to the stress concentration occurs, and steering stability, noise, and vibration performances of the vehicle are negatively impacted.
Further, when an impact is applied to the periphery of the door opening part such as a rear impact case, it is desirable to prevent deformation of the door opening part as far as possible from the viewpoint of safety.
Above all, a corner part that is a joint part between the rear panel and the rear pillar is easily deformed due to stress concentration during impact.
Therefore, a variety of techniques have been proposed in order to enhance the rigidity of the corner part.
For example, in Patent Document 1, a reinforcement is arranged at an inner portion of the corner part, an outer edge of an upper part of the reinforcement is joined to a joint part between an outer edge of a roof panel and an inner edge of a roof side outer, and an inner edge of the upper part of the reinforcement is joined to a joint part between an outer edge of a backdoor opening inner and an inner edge of a roof side inner. Further, an outer edge of a lower part of the reinforcement is joined to a rear end part of the roof side outer, and an inner edge of the lower part of the reinforcement is joined to a backdoor opening flange or a peripheral part of the backdoor opening flange.